lkml.org 
[lkml]   [2019]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: kmemleak panic
From
Date
On 21/01/2019 15:42, Rob Herring wrote:
> +Mike Rapoport
>
> On Mon, Jan 21, 2019 at 8:37 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
>>
>> On Mon, Jan 21, 2019 at 07:35:11AM -0600, Rob Herring wrote:
>>> On Mon, Jan 21, 2019 at 6:19 AM Robin Murphy <robin.murphy@arm.com> wrote:
>>>>
>>>> On 21/01/2019 11:57, Marc Gonzalez wrote:
>>>> [...]
>>>>> # echo dump=0xffffffc021e00000 > /sys/kernel/debug/kmemleak
>>>>> kmemleak: Object 0xffffffc021e00000 (size 2097152):
>>>>> kmemleak: comm "swapper/0", pid 0, jiffies 4294892296
>>>>> kmemleak: min_count = 0
>>>>> kmemleak: count = 0
>>>>> kmemleak: flags = 0x1
>>>>> kmemleak: checksum = 0
>>>>> kmemleak: backtrace:
>>>>> kmemleak_alloc_phys+0x48/0x60
>>>>> memblock_alloc_range_nid+0x8c/0xa4
>>>>> memblock_alloc_base_nid+0x4c/0x60
>>>>> __memblock_alloc_base+0x3c/0x4c
>>>>> early_init_dt_alloc_reserved_memory_arch+0x54/0xa4
>>>>> fdt_init_reserved_mem+0x308/0x3ec
>>>>> early_init_fdt_scan_reserved_mem+0x88/0xb0
>>>>> arm64_memblock_init+0x1dc/0x254
>>>>> setup_arch+0x1c8/0x4ec
>>>>> start_kernel+0x84/0x44c
>>>>> 0xffffffffffffffff
>>>>
>>>> OK, so via the __va(phys) call in kmemleak_alloc_phys(), you end up with
>>>> the linear map address of a no-map reservation, which unsurprisingly
>>>> turns out not to be mapped. Is there a way to tell kmemleak that it
>>>> can't scan within a particular object?
>>>
>>> There was this patch posted[1]. I never got a reply, so it hasn't been applied.
>>>
>>> https://patchwork.ozlabs.org/patch/995367/
>>
>> Thanks Rob, I wasn't aware of this patch (or I just missed it at the
>> time).
>>
>> I wonder whether kmemleak should simply remove ranges passed to
>> memblock_remove(), or at least mark them as no-scan.
>
> Seems reasonable to me, but of course that impacts a lot of other
> cases. Maybe Mike R has some thoughts?

In particular, might that risk crippling kmemleak on EFI arm64 EFI,
where we memblock_remove() the entire physical address space (but then
rebuild the memblock list from scratch)?

FWIW, from the reserved-memory angle I think that patch looks reasonable
as-is (modulo perhaps a kmemleak_no_scan_phys() wrapper for API
symmetry). MEMBLOCK_NOMAP is already a massive pain in the bum and I'd
really rather not introduce any more usage of it if at all possible.

Robin.

\
 
 \ /
  Last update: 2019-01-21 16:54    [W:0.072 / U:159.664 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site